Display label not index in a grid

How can display the label of the choice and not the index in the grid . The data is being fetched form lookup table ( RECORD type),while the document table is a CDT.  

       example on how i display the dropdowns
       
         a!dropdownField(
                label: "Main Type",
                labelPosition: "ABOVE",
                placeholder: "--- Select a Value ---",
                choiceLabels:local!type['recordType!{myrecord} Main Type.fields.{myrecord}descEn'],
                choiceValues: local!type['recordType!{myrecord} Main Type.fields.{myrecord}itemCode'],
                value:ri!DocDetails.mainType,
                saveInto: {ri!DocDetails.mainType},
              
                searchDisplay: "AUTO",
                required: true,
                validations: {}
              )

 a!textField(
                  value:fv!item.id,
                  saveInto:fv!item.id,
                  readOnly: true,
                  align: "CENTER"
                ),

                a!textField(
                  value: fv!item.docForm,
                  saveInto:  fv!item.docForm,
                  readOnly: true,
                  align: "CENTER"
                ),

                a!textField(
                  value:fv!item.mainType,
                  saveInto:  fv!item.mainType,
                  readOnly: true,
                  align: "CENTER"
                ),